In the technical fields of precision linear displacement measurement, in recent years, a new type of time-grating sensor has been developed in China. This time-grating sensor uses a clock pulse as the reference for displacement measurements. And based on the foregoing, a time-grating linear displacement sensor based on alternating electric field has been further developed. The patent application document for this sensor has been published on Dec. 21, 2011 with its Title of Invention as “Time-grating linear displacement sensor based on alternating electric field” and a patent number of 201110145967.5.
The proposed time-grating linear displacement sensor based on alternating electric field has adopted a differential capacitance structure, which functions by using two rows of electrodes to form two channels of standing wave signals, and then the two channels of standing wave signals are combined into a traveling wave signal by an adding circuit. However, it has been noted that the two rows of electrode signals may interfere with each other, which may lead to an increase of measurement errors, and thus hinder further improvements in its measurement accuracy. On the other hand, concerning its manufacturing process, it is difficult to ensure a consistency between the two rows of electrodes; In addition, concerning its installation, it is difficult to ensure consistent electric field coupling strengths between the two rows of electrodes as well. As a result, the foregoing issues may result in an inconsistency in amplitude of the generated two channels of standing wave signals, which will lead to measurement errors and thus compromise its applications in industrial field.